Dyneema fabric will
stop bullets

The Dutch group DSM has developed a nonwoven fabric, 'Dyneema
UD66', for use in bullet-resistant vests. Made from DSM's 'Dyneema SK66' gel-spun polyethylene fibre, the fabric is claimed
to be extremely effective at stopping bullets ...

Reference 1

Developments in design of ballistic protective systems
- III

Design of ballistic protection system depends on the threat
level of the victim, says Dr A K Rakshit and M A Hira

UD - 66

UD stands for ‘uni-directional’ in Dyneema (UHMPE) yarns. In UD all the fibres are laid parallel, in the
same plane, rather than being woven together. Dyneema UD is made of several layers of Dyneema fibres, with the direction of
fibres in each layer at 90 to the direction of the fibres in the adjacent layers. The uni-directional configuration of the
fibres in Dyneema UD allows the energy transferred from the impact of a bullet or other threat to be distributed along the
fibres much faster and more efficiently than in conventional woven fabrics. This is because the absorption power of the yarn
in woven fabrics. This is because the absorption power of the yarn in woven fabrics is poor at the crossover points, as these
points reflect rather than absorb the shockwaves of the impact. In Dyneema UD, much more of the material is engaged in stopping
the bullet, making it more effective against ballistics.

In applying the engineering model it was necessary to assume a maximum breaking stress corresponding
to a strain in the composite about 6.46 %, which greatly exceeds the maximum static strain that this material
can support although dynamic tests carried out using a Hopkinson Bar device lead to values of the critical strain close to
5 %.